Subsurface modifier has no "render" option
If you enable "Experimental" features (it looks like you have done that)



the subdivision modifier changes a bit and it allows "adaptive" subdivisions. You are not forced to use it though.

To not use the adaptive feature, just use the "Levels:" slider under it: it works exactly as the "Render:" slider works in the non-experimental version.



(you can switch back and forth, the value stays the same)